The requirements are listed below. The module may work under different conditions, but has only been tested by our developers in these scenarios. This article assumes that your system, server and PHP installation meets the requirements of WHMCS itself. Their requirements can be found here https://docs.whmcs.com/System_Requirements

System Requirements

Clear understanding of using WHMCS as well as uploading, installing and configuring addons and gateways

PHP 5.6 or higher

WHMCS 7.x (we do not support alpha, beta or release candidate builds)

OpenSSL (or any SSL library) w/ TLS 1.1+ support

Ioncube loader v10.1.x or higher

PHP Extension Requirements

cURL w/ TLS 1.1+ support

DOM

Hash

OpenSSL

Apple Requirements

An Apple Developer account – If you do not have one, you may signup / purchase here